The present invention is in the field of flexible multilayer packaging films and packages made thereof for “cook-in” packaging applications. More specifically, the present invention relates to flexible multilayer packaging films for “cook-in” packaging which have an “easy-opening” feature.
Food items are often cooked in flexible packaging films by immersing the package in hot water or placing the package in a steam-heated environment. This process is referred to in the art as a “cook-in” process and the film used in the process is known as a “cook-in” film or “cook-in” packaging film. Food items which have been cooked and packaged may then be refrigerated, shipped to a retailer, and stored until the cooked food item is consumed, e.g., sliced and repackaged into smaller portions for consumer display. Alternatively, the cooked food items may be immediately removed from the package and either consumed or sliced and repackaged for consumer display.
Flexible films for cook-in packaging applications must be structurally capable of withstanding exposure to cook-in time and temperature conditions while containing the food item. Cook-in time and temperature conditions typically involve a long, slow cook, for example, submersion in hot water at about 55° C. to 65° C. for about 1 to about 4 hours. Submersion in water or steam at 70° C. to 100° C. for up to 12 hours is also possible.
Often the package forming process for cook-in applications, requires that two film surfaces sealed together by heat sealing around the edges of the package to secure a food item therebetween. The sealing of the two film surfaces is typically done using heated sealing bars or similar equipment. Opening of the package obtained in this way usually requires the use of scissors, knives or other cutting devices. It is often desirable to open a package without the use of scissors or knives. One method which obviates the need for a cutting tool in opening a package is the use a packaging film having an easy-opening feature.
“Easy-open” packaging have been used in a variety of food packaging applications to provide packaging that is easy for the consumer to open without having to tear the packaging. Food packaging having a “easy-open” feature may take several forms. For example, a flexible film lidding or lid stock material may be peelably adhered to a rigid tray, tub, or container. Alternatively, the easy-open packaging may incorporate a frangible or peelable seal between a combination of one or more of flexible films, webs, substrates, or supports. Examples of this alternative include thermoforming and vacuum skin packaging methods known in the art. For example, the lower web or support (e.g., “formed web”) may be heated and deep-drawn to form a receptacle for the item to be packaged. Once the item is placed on the support, the upper web (e.g., “non-formed web”) is drawn over the item and peelably sealed to the peripheral edges of the support. The seal may be formed using heated sealing bars, platens, or frames to apply heat and pressure to the top and bottom webs in the seal area.
Other types of easy-open packaging may be formed using vertical-form-fill-seal (VFFS) or horizontal-form-fill-seal (HFFS) methods known in the art to form a pouch or bag containing the packaged product. In such alternatives, the frangible film or web may in effect be sealed to itself (i.e., the same type of film material may form both the top and bottom web of the packaging).
Accordingly, it is desirable to develop flexible packaging films which maintain their structural integrity while being exposed to cook-in times and temperature conditions and are also easily opened without the use of ancillary cutting tools. It is also desirable to develop an easy-open or frangible packaging films which are thermoformable for use in storing and cooking food items contained therein.